IS31BL3230

IS31BL3230
8 CHANNELS CONSTANT CURRENT LED DRIVER
WITH PWM BRIGHTNESS CONTROL
March 2015
GENERAL DESCRIPTION
FEATURES
The IS31BL3230 provides eight regulated current
sources, each delivers up to 90mA of load current with
careful selection of external sense resistors, all outputs
at the IS31BL3230 may be connected in parallel to
enable the current through the LED to be as high as
720mA.
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The IS31BL3230 does not include a charge pump and
therefore has no noise and significantly improved the
efficiency. The external resistor, RSET1, determines the
constant current output of ports LED1 thru LED4, while
resistor RSET2 determines the constant current output of
ports LED5 thru LED8.
Brightness can be controlled with PWM techniques. The
constant current source is set with two external sense
resistors.
Ultra low headroom voltage
Total output current can be 720mA
Cost effective LED driver
Current adjustable via external resistors
Best noise and efficiency performance
Highly integrated design, minimal component
1.6μA (Typ.) shutdown current
Small package QFN-16 (3mm×3mm)
APPLICATIONS
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Flash LED driver
Backlight LED driver
Alternatively, a PWM signal applied to the PWM pin can
vary the perceived brightness of the LED. The device is
in shut down mode when the PWM Input is logic low.
TYPICAL APPLICATION CIRCUIT
Figure 1
Typical Application Circuit for Flash LED Driving
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Rev. B, 02/09/2015
1
IS31BL3230
Figure 2
Typical Application Circuit for 8 LEDs Driving
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Rev. B, 02/09/2015
2
IS31BL3230
PIN CONFIGURATION
16 LED3
15 LED4
14 LED5
13 LED6
ISET1 6
VCC 7
PWM 8
Pin Configurations (Top View)
5
Package
PWM
QFN-16
PIN DESCRIPTION
No.
Name
Description
1
LED2
Current source outputs 2.
2
LED1
Current source outputs 1.
3, 7
VCC
Input voltage.
4, 10
GND
Ground.
5, 8
PWM
PWM brightness control.
6
ISET1
Current set 1 input.
9
ISET2
Current set 2 input.
11~16
LED8~LED3
Current source outputs 8~3.
Thermal Pad
Connect to GND.
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Rev. B, 02/09/2015
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IS31BL3230
ORDERING INFORMATION
Industrial Range: -40°C to +85°C
Order Part No.
Package
QTY/Reel
IS31BL3230-QFLS2-TR
QFN-16, Lead-free
2500
Copyright © 2015 Integrated Silicon Solution, Inc. All rights reserved. ISSI reserves the right to make changes to this specification and its products at any time without notice. ISSI assumes no liability arising out of the application or use of any information, products or services described herein. Customers are advised to obtain the latest version of this device specification before relying on any published information and before placing orders for products. Integrated Silicon Solution, Inc. does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can reasonably be expected to cause failure of the life support system or to significantly affect its safety or effectiveness. Products are not authorized for use in such applications unless Integrated Silicon Solution, Inc. receives written assurance to its satisfaction, that: a.) the risk of injury or damage has been minimized; b.) the user assume all such risks; and c.) potential liability of Integrated Silicon Solution, Inc is adequately protected under the circumstances
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Rev. B, 02/09/2015
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IS31BL3230
ABSOLUTE MAXIMUM RATINGS
Supply voltage, VCC
PWM
Maximum junction temperature, TJMAX
Storage temperature range, TSTG
Operating temperature range, TA
ESD (HBM)
ESD (CDM)
-0.3V ~ +6.0V
-0.3V ~ VCC+0.3V
150°C
-65°C ~ +150°C
-40°C ~ +85°C
3kV
1kV
Note:
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only
and functional operation of the device at these or any other condition beyond those indicated in the operational sections of the specifications is
not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
Unless otherwise specified or noted, VCC = 3.6V, RSET=7.5kΩ, VLEDX=0.5V. Limits apply for TA=25°C. (Note 1)
Symbol
Parameter
Condition
Min
Typ.
Units
5.5
V
VCC
Supply voltage
ILEDX
Output current regulation
VLEDX =0.4V~2.0V, RSET = 7.5kΩ
16
mA
VHR
Minimum headroom
voltage (LEDX)
RSET= 7.5kΩ, ILEDX=20mA
44
mV
VSET
ISET pin voltage
1.2
V
ILEDX/ISET
Output current to current
set ratio
100
mA/mA
ICC
Quiescent supply current
ILEDX = 0mA, ISET= Float
244
μA
IPWM
Shutdown supply current
VPWM=0V
1.6
μA
VPWM_H
PWM input logic high
VCC = 3.0V~5.5V
VPWM_L
PWM input logic low
VCC = 3.0V~5.5V
PWM pin current
VPWM = 1.5V
IPWM
2.7
Max
1.4
V
0.4
5.6
V
μA
Note 1: Production testing of the device is performed at 25°C. Functional operation of the device and parameters specified over other
temperature range, are guaranteed by design, characterization and process control.
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Rev. B, 02/09/2015
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IS31BL3230
FUNCTIONAL BLOCK DIAGRAM
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Rev. B, 02/09/2015
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IS31BL3230
TYPICAL PERFORMANCE CHARACTERISTICS
45
RSET = 3.0kΩ
IN =
3.3V
VVCC
=3.3V
40
RSET = 4.0kΩ
30
25
RSET = 6.0kΩ
20
RSET=6.0k
LED Current (mA)
LED Current(mA)
35
RSET = 7.5kΩ
15
RSET=7.5k
RSET=12.0k
RSET = 12.0kΩ
10
V
=3.3V
VCCIN=3.3V
VLEDX=0.2V
5
0
0
50
100
150
200
Output Voltage(VLEDX)(mV)
Figure 3
Power Supply(V)
Output Voltage vs. LED Current
Figure 4
290
45
RSET = 7.5kΩ
IN =
3.3V
VVCC
=3.3V
40
280
35
270
LED Current(mA)
Quiescent Current(µA)
Power Supply vs. LED Current
260
250
240
30
25
20
15
10
230
220
5
3
3.5
4
4.5
5
0
3
8
Power Supply(V)
Figure 5
Power Supply vs. Quiescent Current
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Rev. B, 02/09/2015
13
18
23
28
30
RSET(kΩ)
Figure 6
RSET vs. LED Current
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IS31BL3230
APPLICATION INFORMATION
CIRCUIT DESCRIPTION
PWM BRIGHTNESS CONTROL
The IS31BL3230 is a white-LED driver with eight
matched current outputs. The matched current
regulators each has a 100:1 current ratio between the
LEDX outputs and the ISET currents. The mirror controls
the current through the LEDs without the use of
external ballast resistors. With a total of 720mA of total
output current available, the IS31BL3230 is capable of
providing 90mA to each of the eight outputs through
the proper selection of the RSET1 & RSET2 resistor. LED
brightness control can be achieved on the IS31BL3230
with PWM signal.
Brightness control can be implemented by pulsing a
signal at the PWM pin.
SHUTDOWN
When the voltage on the active-high-logic PWM pin is
low, the IS31BL3230 will be in shutdown mode. While
disabled, the IS31BL3230 typically draws 1.6μA form
the power supply. There is no internal pull-up or
pull-down on the PWM pin of the IS31BL3230.
OUTPUT CURRENT CAPABILITY
The IS31BL3230 can provide up to 40mA of current to
each of the eight outputs given an input voltage of 2.7V
to 5.5V. An external resistor can be used to set the
output current, as approximated with the following the
equation:
RSET1, 2=100 × (VISET1, 2 / ILEDX)
RSET1 determines the constant current output of ports
LED1 thru LED4, RSET2 determines the constant
current output of ports LED5 thru LED8, VISET is the
voltage of RSET resistance, it is 1.20V typically. In order
for the output currents to be regulated properly,
sufficient headroom voltage (VHR) is required. The
headroom voltage refers to the minimum amount of
voltage that must be present across the current source
in order to ensure the desired current is realizable. To
ensure the desired current is obtained, using the
following equations to find the minimum input voltage
required:
VCC - VLEDX ≥ VHR
VLEDX is the diode forward voltage; VHR is typically as
shown in table1.
Table 1 ILED, RSET and VHR-MIN, VCC=3.6V
ILED
RSET
VHEADROOM
10.0mA
16.0mA
20.0mA
30.0mA
40.0mA
43.8mA
62.5mA
87.5mA
12.0kΩ
7.5kΩ
6.0kΩ
4.0kΩ
3.0kΩ
2.7kΩ
2kΩ
1.4kΩ
27mV(typ.)
44mV(typ.)
53mV(typ.)
66mV(typ.)
75mV(typ.)
100mV(typ.)
150mV(typ.)
210mV(typ.)
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Rev. B, 02/09/2015
The RSET value should be selected using the RSET
equation. The LED brightness is proportional to the
duty cycle (D) of the PWM signal. The PWM frequency
(f) should be limited to accommodate the turn-on time
(tON=50μs) of the device.
D × (1/f) > tON
fMAX = DMIN / tON
If the PWM frequency is much less than 100Hz, flicker
may be seen in the LEDs. For the IS31BL3230, zero
duty cycle will turn off the LEDs and a 50% duty cycle
will result in an average ILED being half of the
programmed LED current. For example, if RSET is set
to program 16mA, a 50% duty cycle will result in an
average ILED of 8mA, ILED being half the programmed
LED current. RSET should be chosen not to exceed the
maximum current delivery capability of the device.
LED SELECTION
The IS31BL3230 has ultra low headroom voltage and
it is designed to drive white-LEDs with a typical forward
voltage up to 3.5V.
As the voltage drop below the recommend VHR, the
drive current will automatically scale down to reduce
the LED current consumption.
POWER DISSIPATION
The maximum allowable power dissipation that this
package can handle is determined by the following:
PDMAX = (TJMAX - TA)/θJA
Where TJMAX is the maximum junction temperature, TA
is the ambient temperature and θJA is the
junction-to-ambient thermal resistance of the specified
package. The IS31BL3230 come in the QFN-16
3mm×3mm package, and it has a junction-to-ambient
thermal resistance (θJA) equal to 34.5°C/W. This value
of θJA is highly dependant upon the layout of the PC
board. The actual power dissipated by the IS31BL3230
follows the equation:
PDISS = (VCC ×ICC) - N(VLEDX × ILEDX)
Where N equals the number of active outputs, VLEDX is
the LED forward voltage, and ILEDX is the current
supplied to the LED.
INPUT CAPACITOR SELECTION
The IS31BL3230 is designed to run off of a fixed input
voltage. Depending on the stability and condition of
this voltage rail, it may be necessary to add some
small input capacitors to help filter out any noise that
may be present on the line. In the event that filtering is
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IS31BL3230
needed, surface-mount multi-layer ceramic capacitors
are recommended. These capacitors are small and
inexpensive. Two capacitances, a 0.1μF and a 1μF are
typically sufficient.
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Rev. B, 02/09/2015
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IS31BL3230
CLASSIFICATION REFLOW PROFILES
Profile Feature
Pb-Free Assembly
Preheat & Soak
Temperature min (Tsmin)
Temperature max (Tsmax)
Time (Tsmin to Tsmax) (ts)
150°C
200°C
60-120 seconds
Average ramp-up rate (Tsmax to Tp)
3°C/second max.
Liquidous temperature (TL)
Time at liquidous (tL)
217°C
60-150 seconds
Peak package body temperature (Tp)*
Max 260°C
Time (tp)** within 5°C of the specified
classification temperature (Tc)
Max 30 seconds
Average ramp-down rate (Tp to Tsmax)
6°C/second max.
Time 25°C to peak temperature
8 minutes max.
Figure 7
Classification Profile
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Rev. B, 02/09/2015
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IS31BL3230
PACKAGE INFORMATION
QFN-16
Note: All dimensions in millimeters unless otherwise stated.
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Rev. B, 02/09/2015
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IS31BL3230
LAND PATTERN
Note:
1. Land pattern complies to IPC-7351.
2. All dimensions in MM.
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Rev. B, 02/09/2015
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